海洋理工学会誌
Online ISSN : 2188-3262
Print ISSN : 1341-2752
ISSN-L : 1341-2752
4 巻 , 1 号
選択された号の論文の9件中1~9を表示しています
原著
  • 仁科 文子, 深澤 理郎
    1998 年 4 巻 1 号 p. 1-10
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    海上保安庁水路部によるWOCE(WorldOceanCii℃ulationExpenment)Pi℃P2観測資料と,水産庁による WHP(WOCEHydrographicProgram)P2観測資料を用いて東西両境界を除く北太平洋で,中層塩分極小の 海域的な特性を記述した。解析は,等密度面上ではなく,塩分極小面上で行われた。その結果,北緯30度 に沿って見る限り,北太平洋中層塩分極小は,西経160度付近を境界として,密度,塩分,溶存酸素量の 空間分布形態が大きく異なっている事がわかった。この結果は,北太平洋中層塩分極小の形成機構および その海域が単一ではない事を強く示唆している。
  • 久保田 雅久, 岡本 哲彦, 平林 克基, 横田 秀和
    1998 年 4 巻 1 号 p. 11-22
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    いろいろな風に対する北太平洋の順圧応答を数値モデルを利用して調べた。用いた風のデータはモデル 解析データとしてヨーロッパ中期予報センターのデータ,海上観測データとしてはCOADSのデータ,衛 星データとしてはGeosatとSSM/Iのデータである。1年間で平均した流れのパターンについては,風の データによる依存性はそれほど大きくないが,流量などの定量的な面については,それぞれの風データの 時空間解像度にかなり依存することがわかった。データの種類のよる定量的な相違は,瞬間値に対しては 平均値と比較してより顕著に見られる。得られた流れのパターンを船の偏流データから推定した表面流の パターンと比較した結果,両者は非常に良く一致した。
  • Rui Chen, Masatoshi Akiyama, Yasuhiro Sugimori, Naoshiro Matsuura, Min ...
    1998 年 4 巻 1 号 p. 23-34
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Compared with historically accumulated hydrographic and nutrients measurements taken at sea, total inorganic carbon dioxide (TCO2) data are far from enough to produce a gridded map ping of high resolution on a global scale, which is crucial to evaluate the carbon budget in the oceans and provide initial values to constrain the biochemical models. In order to get a better understanding of TCO2in the oceans and contribute the large historical database to TCO2estima tion, TCO2 properties and its relation with nutrients in the world oceans are presented and dis cussed using ship data from several international programs, especially recent WOCE cruises dur ing which the accuracy of TCO2 measurements are believed to have been significantly improved. Based on these, a new parameterization method is proposed and tested to estimate TCO2 below the upper oceans (> 400 m) where its seasonal variations are comparatively small. Compared with the ship data which have not been involved in the parameterization procedure, the mean bias and standard deviation are 0.8 u.mol/kg and 7.0 u.mol/kg respectively for Pacific Ocean, while they are 0.5 u.mol/kg and 5.4 u.mol/kg respectively for Atlantic Ocean. Calculated TCO2 in the global oceans can be obtained at Levitus grid point (1°x1°) from 400 m down to the depth of 5,500 m, including vast ocean areas where field investigations ofTCO2 have never been performed.
  • 鈴木 輝明, 青山 裕晃, 甲斐 正信
    1998 年 4 巻 1 号 p. 35-40
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    The mortality of the Japanese littleneck clam (Ruditapes phillippinarum), caused by a decline in bottom dissolved oxygen (DO) concentration, in the shallow muddy bottom of Mikawa Bay, was measured throughout a 50 day period during the early summer of 1996. Using that data, it was attempted to compute the change in mortality as a function of change in DO. When the percentage of DO saturation was considered as the only factor affecting mortality, it did not fit the observed mortality, however it did fit when water temperature was included as an additional factor. Decline of the standing stock of macro-benthos and meio-benthos in the same area was well represented by this mortality function. It was also suggested that meio-benthos mortality in lower temperature than 25 degree is larger than that of macro-benthos.
  • 西村 清和, 鈴木 重教, 徳岡 隆夫
    1998 年 4 巻 1 号 p. 41-54
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Wehave developed a multi-sensor, salinity/temperature measurement system based on the XCTD (Expendable Conductivity, Temperature & Depth Profiling System). The system utilizes five modified XCTD probe as its CT sensors. Each CT sensor is connected with a 500m long multiwire cable at intervals of 50 m, and the cable is connected at its end to a measurement control and data logging system consisting of a notebook computer and peripheral components on land. The CT sensors are installed on the bottom of brackish water lakes and tidal rivers. The CT sensors are switched on in turn by computer control, and the measurement of conductivity and temperature is carried out. Salinity is calculated using measured conductivity and temperature data recorded inside the computer. The system has following features. (1) On-line system. The system allows to get measurement data in real time. (2) Digital system. Digital output data of the CT sensor can transmit on the cable of maximum 10 km length. (3) The sensors have high sensitivity and accuracy. (4) Low cost sensors are used. As the results of observation experiment carried out for two months in River Gonokawa and Lake Nakaumi located in western part of Honshu, Japan, salinity and temperature data were suc cessfully obtained. The system could detect the movement of the salt water in a tidal river and a brackish lake.
  • 石井 憲, 山越 康行, 御手洗 哲司, 有村 忠浩, 廣田 修一
    1998 年 4 巻 1 号 p. 55-64
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    We developed a prototype of a dynamic positioning buoy using DGPS (Differential Global Positioning System). The research budget provided by the Science and Technology Agency of the Japanese Government (the Special Coordination Founds) since 1993. The research is principally aimed at developing of oceanographic vertical observation buoy system to keep the position within a specific area, such as a drifting warm-core ring. The prototype buoy, 5.4m in length, is made of aluminum alloy. A nutrient analysis sensor, sensor for primary production and winch system with cable for vertical sensing are installed in the buoy. Buoy position is self-controlled by using DGPS position data and self-propulsion unit with three electric thrusters. DGPS correction data and position data of the buoy are transmitted via communication satellite. Electric power is supplied by solar and lithium batteries. We carried out full scale trials with significant wave height about 1.4 m, average wind velocity about 5m/sec, buoy drifting velocity about 0.27 m/sec. Dynamic positioning performance and con trolling ability of the vertical sensing system of the buoy are confirmed by these experiments.
  • 鈴木 輝明, 青山 裕晃, 甲斐 正信, 畑 恭子
    1998 年 4 巻 1 号 p. 65-80
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Changes in the nitrogen budget between the sediment and overlying water, were evaluated using a benthic ecosystem model for the shallow area of Mikawa bay, Japan. The model was run for the period between June to July (1996) when a water mass, severely deficient in dissolved oxygen, developed and resulted in drastic benthic community changes. The model result indicated that the nitrogen budget changed greatly as a dissolved oxygen defi cient water mass developed. The shallows had the capability of reducing the particulate organic nitrogen at higher efficiency than the rate of elution of dissolved inorganic nitrogen when ambient oxygen conditions were normal. But, After the oxygen deficient water mass developed, the re moval rate of particulate organic nitrogen decreased with the death of macrobenthic suspension feeders more rapidly than the elution rate in dissolved inorganic nitrogen and consequently, the budget of total nitrogen swinged from sink to source. It is very important to keep the dissolved oxygen saturation level that the benthicfauna can survive to maintain the water purification capacity of the shallows.
  • 堀口 文男, 中田 喜三郎, リー , Woo-Jeung Choi, Cha-Kyum Kim, 寺澤 知彦
    1998 年 4 巻 1 号 p. 81-94
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    In order to evaluate the influence of shellfish farming on water quality, a hydrodynamical and ecological coupled model was applied to Chinhae Bay. We compared results of simulations that included and excluded the presence of farmed shellfishes. From the hydrodynamic simulation, Chinhae Bay has a calm current system except at the mouth. Bay water exchanges with open sea water through the Caduk and Central channels. From the simulation that included farmed shellfishes, it was estimated that shellfishes ingested 34% of phytoplankton primary production (including zooplankton and detrital matter), and egested 70% of that organic matter in the form of fecal pellets. Thus according to the simulation, farmed shellfishes reduced the standing stocks of phytoplankton, zooplankton, and POC from water throughout the Bay by 325 tons, 19 tons, and 821 tons respectively. The phytoplankton biomass in this simulation reduced the organic matter the produce which also means a low COD value (concentration). In contrast, amounts of DIN and DIP increased to 508 tons and 50 tons respectively, through fecal pellets excreted by the shellfishes. The nutrient flux from the sediment also increased as a restul for these pellets depositing on the sea bed. For example, the DIN and DIP flux from the sediment were approximately 10 and 2 times higher than simulations run ex cludingshellfishes. Based on these simulation results, it appears that shellfishfarming has a great impact on the coastal ecosystem.
  • 堀口 文男, 中田 喜三郎, 西田 壽夫
    1998 年 4 巻 1 号 p. 95-122
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    A size-based ecosystem model has been developed to understand a detailed food web system such as a micro-bial loop occurred in a coastal bay (estuary).The model is applied to TokyoBay by coulpling with a 3-D hydrodynamical model. In this application, picoplankton, nano-diatom, nano-flagellate, net-diatom and net flagellate are considered as compartments of autotrophic level. Bacteria, heterotrophic flagellate, micro-zooplankton and meso-zooplankton are considered as compartments of heterotrophic level. According to the sensitivity tests of the model, it is found that the most sensitiveparameterin themodel is the meso-zooplankton grazing rate. Thechange of 0.1 day1 in the meso-zooplankton grazing rate leads to the change of 90 mgCnr3 diatom biomass. The results of the sensitivity analysis show thatthe value of 0.8day1 forthemeso-zooplankton grazing rateis appropriate. The simulated phytoplankton is well reproduced for the present situation inTokyo Bay. The time variations of the simulated biomass of autotrophic components show that diurnal variations caused byphotosynthesis arepredominant. In the heterotrohphic compartments, mesozooplankton biomass also shows typical diurmal variations as a resultof prey-predator interac tion. The net-diatom and net flagellate vary within the period of 10 days in the simulation, and meso-zooplankton also varies with thesame time period but with lags lOdays behind net-phytoplankton, which reflects on the prey-predator interaction. In thesimulation, net-phytoplankton is dominant in the upper bay, whereas nano- and pico plankton becomedominantnear the entranceof the bay. This study demonstrates that the developed model can clarify the temporal and spatial varia tions of each size category and of each trophic level.
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